Facebook CEO Mark Zuckerberg has issued a stern internal memo to employees not to ruin the "Black Lives Matter" movement by defacing Facebook's signature wall that serves as a dry-erase message board at the company's headquarters in California.

The signature wall at the company's Menlo Park headquarters has turned into a graffiti war where employees are crossing out "Black Lives Matter" on the wall and writing "All Lives Matter" instead, said Gizmodo in a report.

The "Black Lives Matter" movement is being observed against the racial profiling and police brutality experienced by the African-American community in the US. "I was already disappointed by this disrespectful behaviour before, but after my communication I consider this malicious as well," Zuckerberg said in the memo.

"We've never had rules around what people can write on our walls. We expect everybody to treat each other with respect," he added. "Black Lives Matter" is an international movement, originating in the African-American community in the US that campaigns against violence towards black people.

The movement began in 2013 with the hashtag #BlackLivesMatter on social media after the acquittal of police official George Zimmerman in the shooting case of African-American teen Trayvon Martin. I hope and encourage people to participate in Black@town hall on March 3-4 to educate themselves about what the "Black Lives Matter" movement is all about, Zuckerberg said.

According to him, there are specific issues affecting the black community in the US, coming from a history of oppression and racism. "Black lives matter" does not mean other lives do not -- it is simply asking that the black community also achieves the justice they deserve.

"Regardless of content or location, crossing out something means silencing speech, or that one person's speech is more important than another's. Facebook should be a service and a community where everyone is treated with respect," the 31-year-old Facebook founder wrote.

"This has been a deeply hurtful and tiresome experience for the black community and really the entire Facebook community, and we are now investigating the current incidents," he noted. "Black Lives Matter" spread further following the death of two African Americans -- Michael Brown in Ferguson and Eric Garner in New York City 2014.